The present application relates generally to apparatus, methods and/or systems concerning the design and operation of turbine rotor blades. More specifically, but not by way of limitation, the present application relates to apparatus, methods and/or systems pertaining to turbine blade tip shrouds with damping and other features.
In a gas turbine engine, it is well known that air pressurized in a compressor is used to combust a fuel in a combustor to generate a flow of hot combustion gases, whereupon such gases flow downstream through one or more turbines so that energy can be extracted therefrom. In accordance with such a turbine, generally, rows of circumferentially spaced turbine rotor blades extend radially outwardly from a supporting rotor disk. Each blade typically includes a dovetail that permits assembly and disassembly of the blade in a corresponding dovetail slot in the rotor disk, as well as an airfoil that extends radially outwardly from the dovetail and interacts with the flow of the working fluid through the engine. The airfoil has a generally concave pressure side and generally convex suction side extending axially between corresponding leading and trailing edges and radially between a root and a tip. It will be understood that the blade tip is spaced closely to a radially outer turbine shroud for minimizing leakage therebetween of the combustion gases flowing downstream between the turbine blades.
As one of ordinary skill in the art will appreciate, due to various stimulus sources during engine operation, rotor blades often exist in a state of vibration or resonance. The sources of vibration generally include rotational imbalance, stator blade stimulus, unsteady pressure perturbations, and combustion acoustic tones. The resulting vibration generally results in the accrual of high cycle fatigue damage, which typically shortens the life of the rotor blade and, in cases where the fatigue causes a blade failure during operation, may lead to catastrophic damage to the turbine engine. The magnitude of the vibration is related at least in part to the amount of damping that is introduced into the system. The more damping that is introduced, the lower the vibratory response, and the more reliable the turbine system becomes. As such, there is a continuing need for improved apparatus, system, and methods for damping and, thereby, reducing the vibration experienced by the rotor blades of turbine engine during operation.